Gluonic excitation of nonexotic hybrid charmonium from lattice QCD

Abstract

The ground and first excited states of the hybrid charmonium $\overline{c}cg$, with nonexotic quantum numbers ${J}^{PC}={0}^{\ensuremath{-}+}$, ${1}^{--}$, and ${1}^{++}$ are investigated using quenched lattice QCD. The excited states are completely ignored in the literature. However, we observe strong gluonic radial excitations in the first excited states; We find their masses are completely different from the first excited states of the corresponding conventional charmonium. Their relevance to the recent discovery of the $Y(4260)$ state and future experimental search for other states are also discussed.